1. Field of the Invention
The present invention relates generally to length measurement, and more particularly, to a length measurement system based on optical recognition and an optical recognition pattern for length measurement.
2. Description of the Related Art
In addition to the traditional measuring ruler, conventional length measurement further includes two kinds of devices; the former is called capacitive digital encoder for measuring length based on capacitive variation resulting from relative movement of two elements having electrodes mounted on the surfaces thereof; the latter is called photoelectric digital encoder for measuring length based on a light source pulse variation resulting from relative movement of two elements having rasters mounted on the surfaces thereof.
The aforesaid conventional measurement devices each have the same principle—accumulative calculation, so they must memorize the initial values and cannot be shut down. Otherwise, they need to be zeroized after shut down and restarted. Thus, they fail to be accessed at any time after restarted, thus being inconvenient in operation.
In addition, in the case of the aforesaid conventional measurement devices, when the user quickly moves the elements having electrodes or rasters mounted on, it tends to happen that the detection of the capacitive change or pulse change cannot keep up with the aforesaid movement in such a way that the outcome of the measurement may not be correct.
In other words, the aforesaid conventional measurement devices and method are defective to need improvement.